1. Field of the Invention
The present invention relates to a keyboard device for an electronic keyboard musical instrument such as an electronic piano, which has a substrate attached through a spacer for detecting information on a key depressed on a keyboard.
2. Description of the Prior Art
FIG. 1 illustrates an exemplary keyboard device for a conventional electronic piano, where one each of black and white keys are shown in an unpressed state. The illustrated keyboard device 31 comprises a multiplicity of keys 33 arranged from left to right (in the depth direction in FIG. 1) (only one each of which is shown); a chassis 32 for supporting the keys 33; a multiplicity of hammers 34 (only one of which is shown) arranged for pivotal movement associated with depression on each key 33; and the like. Each of the keys 33 is pivotably supported by a balance pin 36 (only one of which is shown) implanted on the chassis 32 in a central portion of the key 33 in the longitudinal direction (in a horizontal direction in FIG. 1). The chassis 32 is horizontally fixed to a keybed 35 with screws 35a. 
The hammer 34 is supported by a hammer rail 37. The hammer rail 37 is provided with a plurality of action ribs 39 attached at predetermined intervals in the horizontal direction with a multiplicity of screws 40 (only two of which are shown). Further, a stopper rail 41 is attached to these action ribs 39 with a multiplicity of screws 42 (only two of which are shown), and extend from left to right to cover all the hammers 34. Above the hammer 34, a key switch 45 is further disposed for detecting information on depression on a key 33 associated therewith. The key switch 45 comprises a substrate 46, and a switch body 47 attached to the substrate 46 for each key 33, and is attached to the action rib 39 in the following manner.
First, the substrate 46 is attached to the stopper rail 41 by driving a screw 48 into the stopper rail 41 through a spacer 48 from the lower surface of the substrate 46. Next, with a rear end portion of the substrate 46 inserted into an engaging recess 43a of a fulcrum member 43, the stopper rail 41 is secured to the action rib 39 from above with the screws 42, whereby the key switch 45 is attached to the action rib 39.
In the foregoing manner, the stopper rail 41 is provided separately from the action rib 39, and the stopper rail 41 is attached to the substrate 46, followed by the attachment of the stopper rail 41 to the action rib 39 from above with the screws 42. Such an attachment process is employed by the following reason. If the stopper rail 41 was integrally formed with the action rib 39, the substrate 46 would have to be attached to the action rib 39 from below with screws, in which case the key 33 and hammer 34 would impede a driver from accessing the screws, resulting in difficulties in assembly and disassembly of the keyboard.
Another conventional keyboard device illustrated in FIG. 2 is also known. In the illustrated keyboard device 51, a hammer rail 52 comprises integrally formed hammer rail 37, action rib 39 and stopper rail 41 illustrated in FIG. 1. A cylindrical spacer 66 has been previously formed with a screw hole 66c. For attaching a substrate 56 to the hammer rail 52, a screw 66b is first driven into the screw hole 66c of the spacer 66 through the substrate 56 to attach the substrate 56 to the spacer 66. Next, with one end portion of the substrate 56 inserted into an engaging recess 52a of the hammer rail 52, a screw 66a is driven into the screw hole 66c of the spacer 66 through the hammer rail 52 to attach the substrate 56 to the hammer rail 52 through the spacer 66.
The conventional keyboard device 31 illustrated in FIG. 1, however, has the disadvantage of a large number of required parts and low assembling accuracy due to the separately provided action rib 39 and stopper rail 41. In addition, since the substrate 46 is attached to the stopper rail 41 with the screws 48a, and the stopper rail 41 is also attached to the action rib 39 with the screws 42, a larger number of assembling steps are required, resulting in an increase in the manufacturing cost.
The conventional keyboard device 51 illustrated in FIG. 2 in turn eliminates the aforementioned problem because the hammer rail 52 is composed of the integrally formed action rib 39 and stopper rail 41 in FIG. 1. However, when the spacer 66 is attached to the substrate 56 with the screw 66b, the spacer 66, which rotates together with the screw 66b, causes difficulties in driving the screw 66b into the screw hole 66c. In addition, when the screw 66a is loosened for disassembly, the spacer 66, which rotates together with the screw 66a, causes the screw 66b to readily loosen. For this reason, a rotation preventing tool must be used for preventing such associative rotation, with additional efforts required for this work. The conventional keyboard device 51 has an additional problem of the requirement of expense for previously forming the screw hole 66c in the spacer 66.
The present invention has been made to solve the problems as mentioned above, and it is an object of the invention to provide a keyboard device for an electronic keyboard music instrument which is capable of reducing the manufacturing cost by reducing the number of parts and the number of assembling steps associated with the attachment of the substrate, and of securely attaching the substrate to a chassis through a spacer.
To achieve the above object, a keyboard device for an electronic musical instrument according to the present invention is characterized by comprising a keyboard device for an electronic musical instrument, characterized by comprising a plurality of keys; a chassis for supporting the plurality of keys; a substrate having an engaging hole and attached to the chassis for detecting information on depression on the plurality of keys; a spacer having a tab for preventing rotation and interposed between the substrate and the chassis such that the spacer is attached to the substrate with the tab in engagement with the engaging hole; and a first screw driven into the spacer through the chassis for attaching the substrate to the chassis.
According to this keyboard device for an electronic keyboard musical instrument, the spacer is attached to the substrate by engaging the tab for preventing rotation into the engaging hole of the substrate. The substrate in turn is attached to the chassis with the first screw driven into the spacer through the chassis. Thus, since the spacer is prevented from rotating relative to the substrate by the engaged tab when the substrate is attached to the chassis, the substrate can be readily attached to the chassis without using a special tool for preventing the rotation when the first screw is fastened.
In the foregoing keyboard device, the tab is preferably elastic, and snap fitted into the engaging hole of the substrate.
According to this preferred embodiment of the keyboard device, the tab of the spacer is snap fitted into the engaging hole of the substrate, taking advantage of elasticity, so that the spacer can be readily attached to the substrate in a single motion while it is prevented from coming off.
In the foregoing keyboard device, the spacer is preferably fixed to the substrate with a second screw driven into the spacer through the substrate.
According to this preferred embodiment of the keyboard device, the spacer can be securely fixed to the substrate without saccadic movements by driving the second screw into the spacer through the substrate. In this event, it is possible to omit a process for threading the spacer, as before, by previously forming a lower hole in the spacer and using a tapping screw for the second screw.